Mechanisms of salinity tolerance

Advances in deciphering the mechanisms of salt tolerance in Maize

Maize (Zea mays L.) is a vital crop worldwide, serving as a cornerstone for food security, livestock feed, and biofuel production. However, its cultivation is increasingly jeopardized by environmental challenges, notably soil salinization, which severely constrains growth, yield, and quality. To combat salinity stress, maize employs an array of adaptive mechanisms, including enhanced antioxidant enzyme activity and modulated plant hormone levels, which work synergistically to maintain reactive oxygen species (ROS) balance and ion homeostasis. This review explores the intricate interactions among ROS, antioxidant systems, plant hormones, and ion regulation in maize under salt stress, providing a comprehensive understanding of the physiological and molecular basis of its tolerance. By elucidating these mechanisms, this study contributes to the development of salt-tolerant maize varieties and informs innovative strategies to sustain agricultural productivity under adverse environmental conditions, offering significant theoretical insights into plant stress biology and practical solutions for achieving sustainable agriculture amidst global climate challenges.

Red-emitting fluorescent probe with excellent water solubility for the in situ monitoring of endogenous H2S in wheat under salt and Al3+ stress

Hydrogen sulfide (H2S) is a pivotal signaling molecule in plants and appropriate levels are essential for normal growth. As such the real-time detection of H2S in plants is required since it enables timely targeted interventions. However, most fluorescent probes for detecting H2S reported to date exhibit fluorescence quenching in aqueous solution thereby significantly constraining their potential for in vivo applications. In response to this challenge, we present a natural flavylium-inspired fluorescent probe with robust water solubility for turn-on detection of H2S in organisms. The probe exhibits a remarkable 28-fold turn-on signal at 619 nm with rapid reaction kinetics (-20 min), coupled with high sensitivity (LOD = 0.37 μM) and exceptional selectivity for H2S. By employing the probe as an imaging agent, we managed to successfully visualize the fluctuations of exogenous and endogenous H2S levels in HeLa cells. More importantly, the probe enabled the facile and precise visualization of H2S in stressed wheat roots, achieving remarkable micron-level resolution through in-situ imaging, thereby confirming the upregulation of H2S in response to aluminum ion and salt stress. Our research provides a novel tool to investigate the response and mitigation mechanisms of H2S in plants under diverse stress conditions, as well as strategies for enhancing crop resilience.

Enhanced salt tolerance in Synechocystis sp. PCC 6803 through adaptive evolution: Mechanisms and applications for environmental bioremediation

As a significant environmental challenge, salt stress is common in saline-alkali soils and brackish water, where elevated salt levels hinder the growth of various organisms. Cyanobacteria are ideal models for studying adaptations to salt stress due to their wide distribution across aquatic and terrestrial ecosystems. In this study, we employed adaptive laboratory evolution to increase the salt (NaCl) tolerance of the model cyanobacterium Synechocystis sp. PCC 6803 from 4.0 % to 6.5 % (w/v). Through genome re-sequencing and mutant analysis, six key genes associated with salt tolerance were identified. Notably, overexpression of the slr1753 gene enhanced Na⁺ accumulation on the cell surface, enabling the engineered strain to effectively reduce Na⁺ concentration in seawater by 6.4 %. Additionally, the adapted strain showed promise in remediating saline-alkali soils, with observed increases in the germination rate (184.2 %) and average height (43.8 %) of Brassica rapa chinensis. Soil quality also improved, with a 25.3 % increase in total organic carbon content, a 1.8 % reduction in total salt content, and a 1.9 % decrease in pH. This study provides new insights into the mechanisms underlying salt tolerance and highlights the potential of engineered cyanobacteria for bioremediation in high-salinity environments.

The transcription factor MdWRKY9 is involved in jasmonic acid-mediated salt stress tolerance in apple

Salt stress is an important abiotic stress affecting the growth and fruit quality of apple fruits. Although jasmonic acid (JA) hormones and WRKY transcription factors (TFs) have both been reported to be involved in plant salt stress responses, the molecular mechanisms by which JA-mediated WRKY TFs regulate salt stress in apples remain unclear. Here, we report the identification of a WRKY family TF from apple, MdWRKY9, and its involvement in apple salt tolerance by regulating the expression of Na+/H+ antiporters, MdNHX1, and MdSOS2. Furthermore, we show that the protein repressors MdJAZ5 and MdJAZ10 in the JA signaling pathway can both interact with MdWRKY9 to form a complex and inhibit its DNA-binding and transcriptional activation activity. The JA signal triggers the degradation of MdJAZ5 and MdJAZ10 proteins by the 26S proteasome, disrupting the JAZ-WRKY protein complex and thereby releasing MdWRKY9 to activate downstream gene expression, promoting salt tolerance in apples. These findings provide important insights into the molecular mechanism of the WRKY TFs in JA-mediated salt tolerance in plants.

Vitamin E, total antioxidant capacity and potassium in tomatoes: A triangle of quality traits on the rise

The quality of tomatoes is closely linked to their antioxidant content. However, the contribution of vitamin E to the total antioxidant capacity of these fruits remains unknown, along with its relationship with other components that benefit health. This study examined vitamin E content and composition and their correlation with the total antioxidant capacity in commercial tomato varieties, together with their modulation by abiotic stresses. We also assessed their relationship with other quality parameters such as total soluble sugars, titratable acidity, and sodium and potassium contents. A significant correlation was found between vitamin E content and the total antioxidant capacity, which was greatly influenced by the variety and abiotic stress. Furthermore, a strong association was found between vitamin E and potassium contents. We conclude that vitamin E, the total antioxidant capacity and potassium form a triangle of traits that can be coordinately selected to improve tomato quality.

A microneedle sensor for in-vivo sodium ion detection in plants

This study introduces a novel microneedle-type potentiometric sensor designed for the in-vivo detection of sodium ions (Na+) in plant tissues. The development of this sensor is crucial for advancing our understanding of plant responses to salinity stress. The microneedle sensor employs a highly selective Na+ ion carrier and integrates a solid-contact layer made of poly(3,4-ethylenedioxythiophene)-poly (sodium 4-styrenesulfonate) (PEDOT: PSS) prepared by electropolymerization. Due to its excellent conductivity and high chemical stability, PEDOT:PSS significantly reduces the surface impedance of the electrode, enhances charge transfer efficiency, and thereby improves the sensor's response sensitivity and stability. The sensor achieves a linear detection range of 1 × 10-2 to 1 × 10-5 M, with a slope of 56.55 ± 0.25 mV/decade and a detection limit of 1.94 × 10-6 M. The fabrication process was optimized by refining the membrane formulation, ensuring precise control over membrane thickness, and determining the optimal conditioning time, all essential for large-scale production and agricultural applications. In addition, we evaluated the sensor's ability to detect Na+ concentration changes in both artificial culture media and actual plant tissue samples. The sensor's performance was assessed through its capability to monitor Na+ concentration changes in both artificial culture media and real plant tissue samples, with results benchmarked against the standard method (ICP-OES), confirming its accuracy and reliability. Moreover, application trials involving rice seedlings validated the microneedle sensor's efficacy for in vivo detection of Na+, providing a robust tool for understanding plant physiological responses to salt stress. These findings not only offer new insights into plant adaptation mechanisms but also establish a practical platform for selecting salt-tolerant cultivars and enabling rapid salt-level assessment in agricultural practices.

Effect of salt stress on K+/Na+ homeostasis, osmotic adjustment, and expression profiles of high-affinity potassium transporter (HKT) genes

Salt stress is one of the major threats affecting crop yield. We assessed the behaviour of three barley genotypes, Ardhaoui, Manel, and Testour under 200 mM NaCl with the aim of evaluating the physiological and molecular mechanisms involved in barley salinity tolerance. Results revealed that salinity stress significantly decreases plant growth and water-holding capacity, particularly in the salt-sensitive genotype Testour. Tissue ionic content assessment demonstrated significantly distinct salinity-induced responses. The salt-tolerant genotype Ardhaoui accumulated more K+ and less Na+ content in both leaves and roots compared with the two other genotypes, leading to an increased K+/Na+ ratio. Furthermore, the genotype Ardhaoui exhibited a stronger selectivity transport capacity of K+ over Na+ from root to leaf compared to both Manel and Testour. This effect was due to enhanced K⁺ retention and Na⁺ exclusion, regulated by HvHKT expression. Indeed, higher HvHKT2;1 gene transcript abundance was detected in both leaves and roots of the Ardhaoui genotype, as well as an upregulation of HvHKT1;1 and HvHKT1, mainly in Ardhaoui roots. In view of the severe impact of salinity on plant development, these findings could be applied to the genetic improvement of plant salinity tolerance.

Investigating the Synergistic Interactions Between AgNPs and NiCl2 on the Morpho-Physiological Trajectories of Zea mays L. Through Comprehensive Characterization at Seedling Stage

Green synthesis of nanoparticles (NPs) is preferred for its affordability and environmentally friendly approach. This study explored the synthesis and characterization of silver NPs (AgNPs) and examined their impact on the growth of Zea mays, both alone and in combination with nickel chloride (NiCl2). A methanolic leaf extract was combined with silver nitrate to synthesize AgNPs. Characterization of NPs was carried out through UV-vis spectroscopy, FT-IR, x-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). Eleven treatments (T1-T11) were made, and Z. mays seeds were subjected to NiCl2 in pots after being soaked in AgNPs solution. Treatments were arranged to evaluate the effects of NiCl2 (T1-T3), AgNPs (T4 and T5), and the interactive effects of AgNPs and NiCl2 (T6-T11) on the planted seeds. UV-vis peaks at 410 nm confirmed the presence of AgNPs. The crystalline nature of AgNPs was confirmed through XRD analysis, and the presence of functional groups from biomolecules and capping agents was shown in FT-IR. The morphology of the NPs and elemental analysis were conducted using SEM and EDS, respectively. The size of the NPs was found 25-50 nm using Nano Measurer software. Growth inhibition was noticed in NiCl2-treatments T1-T3. Maximum growth and 100% seed germination were observed in NP-treated seeds (T4 and T5). These two treatments also showed the highest germination index, root/shoot growth, and fresh/dry weights. In treatments T6-T11, the interaction between NiCl2 and AgNP-soaked seeds showed that while AgNP concentrations alone promoted growth, this enhancement was suppressed by the presence of NiCl2 in the soil. The inhibited values of T6-T11 were still greater than the control, indicating that soaking Z. mays seeds in AgNPs enhanced growth and mitigated nickel stress in the soil. Pigments, carbohydrates, and protein contents were highest in T4 and T5, whereas NiCl2 reduced these values. Synthesized AgNPs could enhance Z. mays growth and reduce nickel stress at the applied amounts. Further investigation is required to determine the mechanisms of action of AgNPs and NiCl2 in enhancing or reducing Z. mays seedling growth and yield.

LbHKT1;1 Negatively Regulates Salt Tolerance of Limonium bicolor by Decreasing Salt Secretion Rate of Salt Glands

The HKT-type proteins have been extensively studied and have been shown to play important roles in long-distance Na+ transport, maintaining ion homoeostasis and improving salt tolerance in plants. However, there have been no reports on the types, characteristics and functions of HKT-type proteins in Limonium bicolor, a recretohalophyte species with the typical salt gland structure. In this study, five LbHKT genes were identified in L. bicolor, all belonging to subfamily 1 (HKT1). There are many cis-acting elements related to abiotic/biotic stress response on the promoters of the LbHKT genes. LbHKT1;1 was investigated in detail. Subcellular localization results showed that LbHKT1;1 is targeted to the plasma membrane. Functional analysis in yeast showed that LbHKT1;1 has a higher tolerance than AtHKT1;1 under high Na+ conditions. Silencing and overexpression of the LbHKT1;1 gene in L. bicolor showed that LbHKT1;1 negatively regulates salt secretion by the salt glands. Further experiments showed that LbbZIP52 can specifically bind to the ABRE element in the LbHKT1;1 promoter and regulate the expression of the LbHKT1;1 gene and is involved in the negative regulation of the salt secretion capacity of L. bicolor. This study demonstrates for the first time that the HKT-type protein is involved in salt secretion by salt glands and provides a new perspective on the function of HKT-type proteins under salt stress conditions.

Deep learning based abiotic crop stress assessment for precision agriculture: A comprehensive review

Abiotic stresses are a leading cause of crop loss and a severe peril to global food security. Precise and prompt identification of abiotic stresses in crops is crucial for effective mitigation strategies. In recent years, Deep learning (DL) techniques have demonstrated remarkable promise for high-throughput crop stress phenotyping using remote sensing and field data. This study offers a comprehensive review of the applications of DL models like artificial neural networks (ANN), convolutional neural networks (CNN), recurrent neural networks (RNN), vision transformers (ViT), and other advanced deep learning architectures for abiotic crop stress assessment using different modalities like IoT sensor data, thermal, spectral, RGB with field, UAV and satellite based imagery. The study comprehensively analyses the abiotic stress conditions due to (a) water (b) nutrients (c) salinity (d) temperature and (e) heavy metal. Key contributions in the literature on stress classification, localization, and quantification using deep learning approaches are discussed in detail. The study also covers the principles of deep learning models, and their unique capabilities for handling complex, high-dimensional datasets inherent in abiotic crop stress assessment. The review also highlights important challenges and future directions in deep learning based abiotic crop stress assessment like limited labelled data, model interpretability, and interoperability for robust stress phenotyping. This study critically examines the research pertaining to the abiotic crop stress assessment, and provides a comprehensive view of the role deep learning plays in advancing abiotic crop stress assessment for data-driven precision agriculture.

Overexpression of the Nitraria sibirica Pall. H+-pyrophosphatase gene NsVP1 improves Arabidopsis salt tolerance

Nitraria sibirica Pall., a perennial euhalophytic dwarf shrub, exhibits exceptional salt tolerance and serves as an ideal model species for saline-alkali land remediation, identification of novel salt-responsive genes, and deciphering molecular mechanisms underlying halophytic adaptation. Our previous investigations have shown that salt stress significantly upregulates both the expression and enzymatic activity of vacuolar H⁺-pyrophosphatase (H⁺-PPase) in this species. However, the detailed functional specificity of H⁺-PPase in N. sibirica remains poorly characterized. Here, we cloned and functionally characterized NsVP1, a tonoplast-localized type I H⁺-PPase from N. sibirica. Quantitative real-time PCR (qPCR) analysis revealed that 400mM NaCl treatment induced significant upregulation of NsVP1 expression, resulting in 6.6-fold and 29.4-fold increases in stems and leaves, respectively. Functional characterization studies demonstrated that NsVP1 overexpression in Arabidopsis conferred enhanced salinity tolerance through multifaceted regulatory mechanisms: (1) promoted vacuolar compartmentalization and Na⁺ exclusion via upregulated vacuolar H⁺-PPase activity and synergistic interactions with NHX1 and SOS1, (2) decreased K⁺ loss and maintained cytosolic K⁺/Na⁺ homeostasis, and (3) improved reactive oxygen species scavenging capacity. Notably, the succulent stem and leaf tissues of N. sibirica may enhance its ability to compartmentalize Na⁺, contributing to its superior salt tolerance.

A SnRK2-HAK regulatory module confers natural variation of salt tolerance in maize

The exclusion of sodium ions (Na+) from the shoot tissue, termed shoot Na+ exclusion, underlies a core mechanism of crop salt tolerance. Recent studies have shown that the HAK (High-Affinity K+ Transporter) family Na+ transporters play a key role in shoot Na+ exclusion of various crops, however, it is unknown whether and how this type of transporter is post-transcriptionally regulated. Here, we show that two closely related SnRK2 kinases, designated as ZmSnRK2.9 and ZmSnRK2.10, promote shoot Na+ exclusion and salt tolerance by activating the Na+ transporter ZmHAK4 in maize. Under salt conditions, the kinase activity of ZmSnRK2.9 and ZmSnRK2.10 is activated, then they interact with and phosphorylate ZmHAK4 at Ser5, increasing the Na+ transport activity of ZmHAK4, which in turn promotes salt tolerance by improving the exclusion of Na+ from the shoot tissue. Furthermore, we show that a 20-bp deletion that occurred naturally in the ZmSnRK2.10 promoter decreases its transcript level, resulting in an increased shoot Na+ content under salt conditions. Our findings support a breeding program that can utilize the favorable alleles of ZmHAK4 and ZmSnRK2.10 to enhance both the transcriptional and post-transcriptional activation of ZmHAK4, thus advancing the development of salt-tolerant maize.

Transcriptional mechanisms underlying thiazolidine-4-carboxylic acid (T4C)-primed salt tolerance in Arabidopsis

KEY MESSAGE

T4C enhances salt stress tolerance in Arabidopsis by regulating osmotic and oxidative stress responses, activating ABA-related pathways, and inducing stress-responsive genes, including LEA proteins. High soil salinity is a major environmental stress that restricts crop productivity worldwide, necessitating strategies to enhance plant salt tolerance. Thiazolidine-4-carboxylic acid (T4C) has been reported to regulate proline biosynthesis, which is essential for abiotic stress responses, yet its role in stress tolerance remains unclear. This study investigates the physiological and molecular effects of T4C on Arabidopsis thaliana under salt stress conditions. T4C treatment alleviated salt-induced growth inhibition, improving biomass, relative water content, and chlorophyll retention while reducing oxidative stress markers such as malondialdehyde and anthocyanin accumulation. Transcriptomic and quantitative PCR analyses revealed that T4C upregulated proline biosynthesis genes, ABA-dependent signaling (RD29b, ABI3), and Late Embryogenesis Abundant (LEA) genes. Gene Ontology (GO) enrichment analysis identified biological processes related to water deprivation, ABA signaling, and salt stress, while Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated the involvement of phenylpropanoid biosynthesis, plant hormone signal transduction, and MAPK signaling in T4C-mediated responses. Notably, several transcription factors, including NAC, MYB, and WRKY family members, were identified as candidates involved in T4C-mediated stress priming. Collectively, these findings suggest that T4C may enhance salt tolerance by modulating osmotic balance, reducing oxidative stress, and activating stress-responsive genes and transcriptional regulators. Our results provide novel insights into the molecular mechanisms underlying T4C-mediated stress responses, highlighting its potential as a chemical priming agent to improve plant resilience under saline conditions.

Aeluropus lagopoides: an important halophyte with key physiological and molecular mechanisms for salinity tolerance and a unique genetic resource for developing climate resilient crops

Aeluropus lagopoides is salt secreting halophytic perennial grass that commonly grows in coastal regions. Under excessive saline conditions, A. lagopoides is able to thrive and completes its life cycle. It has developed various adaptive mechanisms to tolerate harsh environmental conditions. Aeluropus follow the novel mechanism of salt secretion by excreting Na+ from the leaf sheath and stem of the plant in the form of salt crystals. Various salt responsive genes and transcription factors have been studied under salinity stress in A. lagopoides. Economically important phytochemicals are also present in this plant, thus, making it industrially important. Utilization of salt stress responsive genes and transcription factors in developing salt tolerant transgenics crops can also provide significant benefits, and potentially boost the agricultural industry for sustainable growth and production.

Effects of exogenous Uniconazole (S3307) on oxidative damage and carbon metabolism of rice under salt stress

BACKGROUND

Salt stress significantly suppresses rice growth. Uniconazole (S3307) is recognized for its potential to enhance plant stress tolerance. Nevertheless, the mechanisms through which S3307 induces salt tolerance in rice by modulating the carbon metabolism pathway are not fully understood. In this study, at the one-leaf-one-heart stage, the foliage of rice HD961 and 9311 was treated with 10 mg·L- 1 S3307, followed by a 0.6% (102.56 mmol·L- 1) NaCl treatment 24 h later.

RESULTS

The results demonstrated that salt stress markedly suppressed the growth of rice aboveground and underground, reduced the net photosynthetic rate (Pn), and ultimately led to a decline in yield. However, salt stress increased the activities of peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) and enhanced sucrose metabolism simultaneously of rice leaves. However, compared to salt stress, foliar spraying of S3307 under salt stress increased rice biomass accumulation, enhanced photosynthetic efficiency, reduced malondialdehyde (MDA) content, and further enhanced the activities of superoxide dismutase (SOD), POD, CAT, and APX. Meanwhile, the application of S3307 effectively further promoted the accumulation of sucrose, glucose, and soluble sugar (SS) in rice leaves under salt stress. It also enhanced the activities of key enzymes in glycolysis, namely hexokinase (HK) and pyruvate kinase (PK), and facilitated the accumulation of α-ketoglutaric acid (α-KG), citric acid (CA), and pyruvate (PA). Meanwhile, it increased the effective panicle number (EPN), grains per panicle, yield per panicle and theoretical yield of rice.

CONCLUSION

Therefore, S3307 can mitigate the damage caused by salt stress and enhance yield and rice resistance by improving photosynthetic characteristics, strengthening the antioxidant system, and promoting physiological activities in carbon metabolism pathways such as Carbohydrate, glycolysis (EMP) and the tricarboxylic acid (TCA) cycle.

Lignin-containing cellulose nanofiber-selenium nanoparticle hybrid enhances tolerance to salt stress in rice genotypes

Soil salinization poses a significant challenge for rice farming, affecting approximately 20% of irrigated land worldwide. It leads to osmotic stress, ionic toxicity, and oxidative damage, severely hindering growth and yield. This study investigates the potential of lignin-containing cellulose nanofiber (LCNF)-selenium nanoparticle (SeNPs) hybrids to enhance salt tolerance in rice, focusing on two rice genotypes with contrasting responses to salt stress. LCNF-SeNP hybrids were synthesized using a microwave-assisted green synthesis method and characterized through FTIR, X-ray diffraction, SEM, TEM, and TGA. The effects of LCNF/SeNPs on seed germination, physiological responses, and gene expression were evaluated under varying levels of NaCl-induced salt stress. Results indicated that LCNF/SeNPs significantly enhanced the salt tolerance of the salt-sensitive genotype IR29, as evidenced by increased germination rates, reduced salt injury scores, and higher chlorophyll content. For the salt-tolerant genotype TCCP, LCNF/SeNPs improved shoot lengths and maintained elevated chlorophyll levels under salt stress. Furthermore, LCNF/SeNPs improved ion homeostasis in both genotypes by reducing the Na+/K+ ratio, which is crucial for maintaining cellular function under salt stress. Gene expression analysis revealed upregulation of key salt stress-responsive genes, suggesting enhanced stress tolerance due to the application of LCNF/SeNPs in both genotypes. This study underscores the potential of LCNF/SeNPs as a sustainable strategy for improving crop performance in saline environments.

Impact of climate on water status, growth, yield, and phenology of coffee (Coffea arabica) plants in the central region of the state of Veracruz, Mexico

Coffee (Coffea arabica) is one of the most widely traded and most consumed agro-products worldwide. Its production is concentrated in tropical regions, and its consumption, in northern countries. Climate variability influences coffee yield and quality, and the distribution of wet and dry periods is closely related to its phenological phases. Recently, the vulnerability of coffee producing regions to changes in climate patterns has been demonstrated. Therefore, this study evaluated the effect of climatic variables on the water status, vegetative growth, yield, and phenology of coffee plants. The research was carried out in a coffee agroecosystem (Garnica variety) located in the central region of the state of Veracruz, Mexico (19.51998∘ N and 96.94339∘ W; 1320 masl). For three years, the phenology of coffee plants was monitored; plant growth (height, number of leaves) and cherry yield were measured each month during three productive periods. Microclimatic variables (temperature, precipitation, relative air humidity, solar radiation, and wind direction) and water-balance variables (infiltration, rainfall interception, transpiration, soil water storage, crop evapotranspiration [ETo], and reference evapotranspiration [ETc]) were also monitored. The water status of the plants was evaluated based on their water demand, determined as the ETc/ETo ratio. The relationship of microclimatic variables with water status, plant growth, and plant yield was measured by performing correlation statistical tests (Pearson; [Formula: see text]), principal component analyses (PCA), and simple and multiple linear regressions. The results show that the highest water consumption occurred during the flowering ([Formula: see text]), and grain ripening ([Formula: see text]) phenological phases, while the lowest value ([Formula: see text]), indicative of water deficit, was observed at harvest for the period 2018-2019. Precipitation (P) and rainfall infiltration (I) are the variables with the greatest influence on vegetative growth (r2>0.70). A relationship was observed between yield and water and microclimatic variables. However, simple and multiple linear regressions, including PCA, explain less than [Formula: see text] (p < 0.05) of the variability of yield data. This variability is mainly described by water conditions related to soil water storage (S) and thermal conditions, particularly the minimum temperature (Tmin). Our findings suggest that the water demand of coffee plants changes significantly with the phenological phases of the crop; therefore, changes in the cyclical patterns of climate variation could cause a water deficit in coffee plants, limiting their development, yield, and quality.

Transcriptomic Analysis Identifies Molecular Response of the Tolerant Alfalfa (Medicago sativa) Cultivar Nongjing 1 to Saline-Alkali Stress

Alfalfa (Medicago sativa) is a perennial forage crop with significant economic and ecological significance. If alfalfa can be planted in saline-alkali land, it will not only improve the utilization rate of marginal land and alleviate the competition between forage and cereal crops for arable land but will also increase the yield of high-quality domestic forage. In this study, we conducted transcriptomic analysis on the saline-alkali-tolerant alfalfa cultivar NQ-1 and compared its metabolite accumulation levels with saline-alkali-sensitive cultivars. The results showed that under saline-alkali stress, the photosynthesis and some secondary metabolic pathways in NQ-1 were activated, such as α-Linolenic acid metabolism, Phenylpropanoid and Flavonoid biosynthesis, and Photosynthesis-related pathways, providing substances and energy for enhancing NQ-1 stress tolerance. Furthermore, some specific flavonoids were detected that may contribute to the saline-alkali tolerance of NQ-1. In addition, transcription factors that may regulate flavonoid biosynthesis in NQ-1 under saline-alkali stress were also identified. This study deepens the understanding of the resistance mechanism of saline-alkali-tolerant cultivars of alfalfa and provides valuable information for molecular design breeding strategies for stress-resistant alfalfa.

Unraveling the complexities: morpho-physiological and proteomic responses of pearl millet (Pennisetum glaucum) to dual drought and salt stress

Agriculture is crucial for sustaining the world's growing population, however various abiotic and biotic stressors, such as drought and salt, significantly impact crop yields. Pearl millet, a nutrient-rich and drought-tolerant crop, is essential as a food source in arid regions. Understanding its response mechanisms to drought and salt stress is important for devising strategies for improved crop performance under water deficit and saline environments. This study investigated the pearl millet's morphological, physiological, and molecular responses subjected to individual and combined drought and salt stresses for 25 days. Significant reductions in morphological traits, such as plant height, shoot and root fresh weights and lengths, and leaf numbers were observed. Furthermore, key physiological parameters, including chlorophyll content, stomatal conductance, photosynthesis, and transpiration rates notably declined, indicating a complex interaction between stress factors and water regulation mechanisms. Protein expression analysis showed differential upregulation and downregulation patterns between the control and stressed pearl millet plants. Gene ontology mapping identified key biological processes, molecular functions, and cellular components of differentially expressed proteins associated with individual and combined stresses. Notably, a high number of unclassified proteins were identified, indicating the presence of potentially novel proteins involved in stress adaptation. Catalytic and binding activities were the predominant molecular functions detected across treatments suggesting their central role in stress response. These highlighted potential mechanisms of tolerance and adaptation in pearl millet. Overall, this study provides a comprehensive understanding of the detrimental effects of drought and salinity on pearl millet at the morphological, physiological, and proteomic levels, uncovering previously unexplored proteomic responses. These insights offer valuable molecular marker targets for breeding programs aimed at enhancing stress tolerance in pearl millet and related crops.

Transcriptome and network analysis pinpoint ABA and plastid ribosomal proteins as main contributors to salinity tolerance in the rice variety, CSR28

Salinity stress is a major challenge for rice production, especially at seedling stage. To gain comprehensive insight into the molecular mechanisms and potential candidate genes involved in rice salinity stress response, we integrated physiological, transcriptome and network analysis to investigate salinity tolerance in two contrasting rice genotypes. The root and shoot samples were collected at two timepoints (6 hours and 54 hours) of high salt treatment. Element assay showed that the tolerant genotype CSR28 had lower Na+/K+ ratio in both organs than in those of the sensitive genotype IR28 under salinity stress. A total of 15,483 differentially expressed genes (DEGs) were identified from the RNA-Seq analysis. The salt-specific genes were mainly involved in metabolic processes, response to stimulus, and transporter activity, and were enriched in key metabolic pathways such as, biosynthesis of secondary metabolites, plant hormone signal transduction, and carotenoid biosynthesis. Furthermore, the results showed that the differential genes involved in abscisic acid (ABA) biosynthesis were specifically up-regulated in the tolerant genotype. Network analysis revealed 50 hub genes for the salt-specific genes in the roots of CSR28 which mainly encodes ribosomal proteins (RPs). Functional validation of the nine hub genes revealed three plastid RPs (PRPs), including OsPRPL17, OsPRPS9 and OsPRPL11, which contributes to protein synthesis, chloroplast development and stress signaling. Our findings suggested that ABA and PRPs play key roles to enhance of salinity tolerance in CSR28. Our study provides valuable information for further investigations of the candidate genes associated with salt tolerance and the development of salt-tolerant rice varieties.

Interpreting the potential of biogenic TiO2 nanoparticles on enhancing soybean resilience to salinity via maintaining ion homeostasis and minimizing malondialdehyde

The use of nanoparticles has emerged as a popular amendment and promising approach to enhance plant resilience to environmental stressors, including salinity. Salinity stress is a critical issue in global agriculture, requiring strategies such as salt-tolerant crop varieties, soil amendments, and nanotechnology-based solutions to mitigate its effects. Therefore, this paper explores the role of plant-based titanium dioxide nanoparticles (nTiO2) in mitigating the effects of salinity stress on soybean phenotypic variation, water content, non-enzymatic antioxidants, malondialdehyde (MDA) and mineral contents. Both 0 and 30 ppm nTiO2 treatments were applied to the soybean plants, along with six salt concentrations (0, 25, 50, 100, 150, and 200 mM NaCl) and the combined effect of nTiO2 and salinity. Salinity decreased water content, chlorophyll and carotenoids which results in a significant decrement in the total fresh and dry weights. Treatment of control and NaCl treated plants by nTiO2 showed improvements in the vegetative growth of soybean plants by increasing its chlorophyll, water content and carbohydrates. Additionally, nTiO2 application boosted the accumulation of non-enzymatic antioxidants, contributing to reduced oxidative damage (less MDA). Notably, it also mitigated Na+ accumulation while promoting K+ and Mg++ uptake in both leaves and roots, essential for maintaining ion homeostasis and metabolic function. These results suggest that nTiO2 has the potential to improve salinity tolerance in soybean by maintaining proper ion balance and reducing MDA level, offering a promising strategy for crop management in saline-prone areas.

Cd Stress Response in Emmer Wheat (Triticum dicoccum Schrank) Varieties Under In Vitro Conditions and Remedial Effect of CaO Nanoparticles

In this study, the mitigating effects of CaO NPs obtained from pomegranate extract via environmentally friendly green synthesis on CdCl2 stress in two varieties (Yolboyu and Kirac) of Turkish Kavilca wheat (Triticum dicoccum Schrank) under in vitro callus culture conditions were investigated. The calluses developed from embryos of both wheat varieties were exposed to either CaO NPs alone (1 and 2 mg/L), CdCl2 alone (1 or 10 mM) or the different combinations of these two compounds in MS medium for 4 weeks. Changes in the expressions of two genes (Traes_5BL_9A790E8CF and Traes_6BL_986D595B9) known to be involved in wheat's response to CdCl2 stress were analyzed by qRT-PCR. Additionally, certain physiological parameters, such as lipid peroxidation (LPO), H2O2, proline and soluble sugar content, and SEM-EDX analysis were used to assess the response of calluses to the applications. The CaO NPs treatments alone generally upregulated the expression of the 5BL and 6BL genes, while the CdCl2 applications decreased their expression in both cultivars. The CaO NPs reduced the proline content in both cultivars compared to the control. Co-treatment with CdCl2 and CaO NPs increased the sugar content and decreased the MDA content, but did not cause a significant change in the H2O2 content. SEM analysis showed that when CdCl2 and CaO NPs were applied to calluses together, the membranous and mucilaginous spherical structures were regained. The application of CaO NPs reduces the amount of cellular damage caused by CdCl2 stress and improves gene expressions.

The Combination of Salicylic Acid, Nicotinamide, and Proline Mitigates the Damage Caused by Salt Stress in Nasturtium (Tropaeolum majus)

Salinity represents a significant challenge for agriculture, especially in semi-arid regions, affecting the growth and productivity of plants such as nasturtium (Tropaeolum majus), which is valued for its ornamental, medicinal, and food uses. Salt stress disrupts biochemical, physiological, and anatomical processes, limiting plant development. This study investigated the application of attenuators, including salicylic acid, nicotinamide, and proline, to mitigate the effects of salt stress on nasturtium cultivated in a hydroponic system. The treatments involved different combinations of these compounds under saline conditions (40 mM NaCl). The attenuators reduced the negative impacts of salt stress, promoting improvements in gas exchange, such as increased net photosynthesis, water-use efficiency, and stomatal conductance. Additionally, the treatments enhanced vegetative and reproductive growth, increasing the dry biomass of leaves, stems, and flowers, as well as the number of flowers and flower buds. The combination of salicylic acid, nicotinamide, and proline stood out by providing greater efficiency in carbon assimilation, stability of photosynthetic pigments, and higher tolerance to salt stress. These findings reinforce the potential of using attenuators to optimize the cultivation of nasturtium in saline environments, promoting higher productivity and plant quality.

Spatial and development responses in the wheat leaf highlight the loss of chloroplast protein homeostasis during salt stress

Salinity stress in wheat affects physiological and biochemical parameters in tissues that alter plant development and ultimately lower crop yield. Shoot tissues can accumulate high concentrations of sodium over time through the transpiration stream coming from the roots. This imposes physiological responses that align salt effects with the basipetal developmental gradient of the monocot leaf. The role of metabolic processes in generating and responding to these increases in sodium concentration over time was explored by linking changes in ion distributions to those of enzyme abundance from the base to the tip of leaves under salt stress. We found that enzymes for methionine synthesis and lipid degradation pathways increase, concomitantly with proteins in jasmonate synthesis, which are key players in plant stress-induced responses. Combining the use of Differential Abundance of Protein analysis and Weighted Correlation Network Analysis we have focused on identifying key protein hubs associated with responses to salt stress or salt susceptibility, shedding light on potential sites of salt sensitivity as targets for enhancing salt tolerance in wheat. We found chloroplast protein synthesis machinery, including the 30S and 50S ribosomal proteins, and plastid localised protein synthesis elongation factors, were significantly reduced in abundance and correlated with the altered K+/Na+ ratio along salt-stressed wheat leaves. Additionally, the plastid protease system including ATP-dependent caseinolytic protease and filamentous temperature-sensitive H proteases involved in chloroplast protein homeostasis, show decreased abundance with salt. The complex interplay of these processes in and across the leaf affects overall plant viability under salt stress mainly affecting the energy homeostasis in wheat shoot. Data are available via ProteomeXchange with identifier PXD059765. SIGNIFICANCE: Soil salinity is a major agricultural challenge that cause significant reduction in wheat yields, a staple crop vital for global food security. Despite extensive breeding efforts, developing salt-tolerant wheat remains challenging due to the complex, multi-genic nature of salinity tolerance. While numerous studies have explored molecular responses to salt stress making salt to control comparisons, there is little consensus on the primary points of metabolic disruptions that would determine the salt response in wheat. Our study addresses this gap by integrating proteomics with Weighted Correlation Network Analysis to examine metabolic responses along the developmental gradient of wheat leaves. By exploiting the natural base-to-tip progression of leaf maturation under salt stress, we identify key protein groups linked to salt response. These findings provide new insights into potential metabolic targets for enhancing wheat's resilience to salinity stress.

Conditioning rice seeds with chitosan to mitigate salt stress

Rice is considered to be moderately salt-tolerant during germination, development, and ripening stages, and environmentally sensitive during seedling and reproductive stages, which affects seedling emergence and growth, resulting in significant yield losses. Seed conditioning with chitosan has been employed as a useful tool in high-salinity environments with the aim of increasing crop productivity and quality, as well as promoting more sustainable agricultural practices. Therefore, this study aimed to examine the effect of seed conditioning with chitosan on seed germination and rice seedling growth under salinity stress. The experiment consisted of three seeds conditioning and 4 salinity levels, arranged in a completely randomized design with 4 replications. Seeds were sown on germitest paper, and the rolls were placed in a germination chamber (25 ± 2°C and 12 hr photoperiod). Germination and seedling growth parameters were determined. The high salt concentration resulted in reduced growth of rice seedlings, and exogenous application of chitosan at different concentrations and soaking times exerted no apparent adverse effect on germination and growth variables. The attenuating effect of chitosan was observed in the length of the seedlings at all the concentrations utilized. Therefore, evidence indicates that conditioning rice seeds with chitosan might serve as an alternative to mitigate the adverse effects of exposure to stress induced by high salt concentrations.

A large-scale gene co-expression network analysis reveals Glutamate Dehydrogenase 2 (GhGDH2_D03) as a hub regulator of salt and salt-alkali tolerance in cotton

Salt stress and salt-alkali stress significantly inhibit the normal growth and development of plants. Understanding the molecular mechanisms of cotton responses to these stresses is crucial for improve yield and fiber quality. In this study, we conducted a comprehensive analysis of the transcriptome dynamics under salt and salt-alkali stress conditions, utilizing 234 RNA-seq datasets compiled from 11 previous studies. After systematic evaluation and correction for batch effects, we observed that root transcriptomes clustered more consistently than leaf transcriptomes across stress treatment and time points. Weighted gene co-expression network analysis (WGCNA) on 123 root transcriptomes identified three key modules, with their hub genes significantly associated with salt and salt-alkali tolerance. Virus-induced gene silencing assay and RNA-seq analysis indicated that GhGDH2_D03 (Gohir.D03G104800), a module hub gene encoding Glutamate Dehydrogenase 2, positively regulates salt and salt-alkali tolerance in cotton by modulating multiple signaling pathways and metabolic processes, including the ethylene signaling pathway. This study underscores the pivotal role of GhGDH2_D03 in conferring tolerance to salt and salt-alkali stress, in addition to its previous reported involvement in biotic stress defense, providing valuable insights and genetic resources for cotton breeding.

Role of calcium acetate in promoting Vibrio campbellii bioluminescence and alleviating salinity stress in Episcia cupreata

This study examines the role of calcium in regulating the bioluminescence of Vibrio campbellii PSU5986 and its potential to alleviate salt stress in plants, which has implications for developing light-emitting plants (LEPs). The effects of organic calcium acetate (C₄H₆CaO₄) were compared to inorganic calcium chloride (CaCl₂) and skim milk regarding their impact on bacterial bioluminescence and plant physiology. While skim milk induced the highest initial luminescence, both C₄H₆CaO₄ and CaCl₂ prolonged light emission for over 16 h. Notably, C₄H₆CaO₄ prevented leaf shrinkage, a condition observed with inorganic salts after 24 h. Periodic supplementation of C₄H₆CaO₄ (every 6 h) improved bacterial immobilization and colonization, extending luminescence over 4 cycles (24 h). Bacterial enumeration revealed colonization densities of approximately 6.82 × 106 CFU cm⁻2 within leaf tissues and 5.22 × 1011 CFU cm⁻2 on the leaf surface. Quantitative PCR analysis indicated that luxG exhibited significantly higher copy numbers than luxA and luxC, highlighting its critical role in bioluminescence through flavin reductase activity. Additionally, C₄H₆CaO₄ reduced salt-induced oxidative stress by increasing chlorophyll levels while decreasing carotenoid (40.00%), anthocyanin (36.94%), proline (14.13%), and malondialdehyde (21.84%) accumulation compared to NaCl-treated plants. These findings emphasize the potential of C₄H₆CaO₄ to sustain bacterial luminescence and enhance plant resilience, contributing to the advancement of LEP technology as a sustainable bioenergy alternative.

Silencing of SbPPC3 reduces the germination capacity in salinity and decreases the nutritional value of sorghum seeds

Sorghum (Sorghumbicolor L.) is the fifth most important cereal crop worldwide and tolerant to drought and salinity. Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) is an enzyme playing key roles in seed development and germination. We have previously demonstrated that the silencing of the non-photosynthetic SbPPC3 gene affects plant growth and productivity, delaying flowering, and reducing seed production. In this work, knock-down lines (Ppc3 lines) were used for assessing the contribution of PPC3 to seed filling and germination. PEPC activity was greatly reduced in dry and germinating seeds although the germination capacity was not affected. This could be due to increased phosphorylation of PPC2, the only PEPC isoenzyme co-expressed in the dry seed stage with PPC3. In salinity, PPC2 does not increase its phosphorylation in Ppc3 lines, and silenced lines show lower germination rate. In addition, the survival of seedlings in salinity was reduced to 25% in Ppc3 plants, whereas it remains close to 80% in WT. Thereby, the importance of PPC3 isoenzyme during seed germination in salinity is stablished. The dry seeds of silenced lines show reduced weight, lower starch and fibers levels, and altered energetic state. Despite lower levels of protein compared to WT seeds, Ppc3 seeds showed lower C/N ratio and higher phytate content, indicating alterations in C, N and P metabolisms. These results show that PPC3 activity affects replenishment of seed reserves, thus altering its nutritional value. In addition, they corroborate the relevance of phosphorylation of a starch-storing-cereal seed PEPC during germination.

The AP2/ERF transcription factor MhERF113-like positively regulates drought tolerance in transgenic tomato and apple

Drought is a major abiotic stress in agriculture that severely affects crop growth, yield, and quality. The APETALA2/ethylene responsive factor (AP2/ERF) plays a crucial role in maintaining plant growth, development, as well as stress tolerance. Herein, we cloned and characterized the MhERF113-like gene from Malus hupehensis. MhERF113-like is significantly induced by drought and highly expressed in leaves. Overexpression of MhERF113-like positively regulated the drought tolerance of apple calli and plants, as judged by less electrolyte leakage, lower malonaldehyde (MDA) and hydrogen peroxide (H2O2) contents in OE than those of the WT apple calli and plants under drought stress. In addition, ectopic expression of MhERF113-like gene in tomatoes improved the drought tolerance, accompanied by enhanced expression of antioxidant genes (SlAPX1 and SlSOD) and stress responsive genes (SlDREB and SlRD29), and reduced H2O2 and O2- contents in OE tomatoes. Taken together, our study demonstrated that MhERF113-like may play an important role in the regulation of plant drought tolerance, which may provide a key factor for future biotechnology applications to improve drought stress tolerance in plants.

AmbHLH091 is released by AmNAC035 and drives Salt Overly Sensitive 1 and Pyrroline-5-Carboxylate Synthase expression to mediate salt tolerance in mangrove Avicennia marina

Avicennia marina is the pioneer species of mangroves suffering from high-saline environment. bHLH is the second largest family of transcription factors (TFs) in plants, and involves in various stress responses. So far, the bHLH family members are not identified and bio-functionally characterized in A. marina. In this study, the 228 AmbHLH family members were identified from A. marina genome. Through bioinformatics analysis, the AmbHLH091 was specifically chosen to elucidate its biological function in salt tolerance. Expression pattern analysis exhibited AmbHLH091 was mainly expressed in leaf, root, and stem tissues, and AmbHLH091 was significantly up-regulated under salinity treatment. Additionally, subcellular localization analysis showed AmbHLH091 was mainly expressed in cell nucleus. The transient overexpression and protein-DNA interaction analysis revealed AmbHLH091 is likely to promote Na+ transport and proline accumulation by interacting with the promoters of Salt Overly Sensitive 1 (AmSOS1) and Pyrroline-5-Carboxylate Synthase (AmP5CS). In yeast expression analysis, the AmbHLH091 enhanced the salt tolerance via promoting the AmSOS1 and AmP5CS expression. Besides, another TF AmNAC035 interacts with AmbHLH091 and negatively regulates AmbHLH091 transcriptional activity, thereby modulating the expression of AmSOS1 and AmP5CS. Summarily, our results revealed AmbHLH091-AmNAC035 macromolecule participates the salt tolerance of A. marina in the coastal saline intertidal habitats.

Enhancing wheat resilience to salt stress through an integrative nanotechnology approach with chitosan proline and chitosan glycine

Salt stress significantly limits wheat production worldwide, jeopardizing food security and sustainable agriculture. Developing strategies to enhance wheat's resilience to salinity is critical for maintaining yield in affected regions. This study investigates the potential of chitosan-proline (Cs-Pro) and chitosan-glycine (Cs-Gly) nanoparticles in mitigating salt stress in salt-tolerant Heydari and salt-sensitive Sepahan wheat cultivars, with a special question on genotype-dependent differences. Plants were treated with nanoparticles at concentrations of 0, 200, and 400 mg L⁻¹ under salt stress levels of 0, 200, and 400 mM NaCl. The salt-tolerant Heydari cultivar exhibited superior adaptability to saline conditions, in addition reacted more positively to nanoparticle treatments. Results demonstrated significant physiological improvements, including increased relative water content (RWC), enhanced chlorophyll content and elevated proline levels, especially after 400 mg L⁻¹ Cs-Pro treatment. Oxidative stress markers, such as malondialdehyde (MDA) and hydrogen peroxide, were substantially reduced, while antioxidant enzyme activity was boosted. Certain stress-responsive genes (e.g., TaADC, TaPxPAO, TaSAMDC, TaSPDS, TaSOS1, TaNHX1) were upregulated, highlighting the importance of ionic balance and polyamine metabolism in improved stress tolerance. The application of Cs-Pro and Cs-Gly nanoparticles presents a promising approach to enhance wheat's salinity tolerance by improving physiological, biochemical, and molecular responses.

Impact of salinity gradients on nitric oxide emissions and functional microbes in estuarine wetland sediments

Estuarine wetland sediments are hotspots for nitrogen cycling and critical sources of atmospheric nitric oxide (NO). Yet studies on the impact of sediment salinity gradients on NO emissions and associated functional microbes at the land-ocean interface remain limited. Here, we measured sediment NO emission rates from incubated sediment samples that were collected from an estuarine wetland in Qingdao, China. Our findings indicate that sediment salinity is a pivotal factor shaping NO emission rates, by altering the community composition and gene abundance of functional microbes involved in NO emissions, with rates ranging from 0.04 to 0.25 μg N kg-1 dry soil h-1. Metagenomic analysis of the sediment samples reveals that greater NO emission rates (+486 %) under salinity changes are linked to a higher abundance of the nirS gene (+26 %) responsible for NO formation and a lower abundance of norBC genes (-23 %) responsible for NO consumption. Accordingly, the increase of NO emissions may be attributed to the accumulation of denitrifying NO, which could improve plant salt tolerance through co-evolutionary interactions between plants and sediment-dwelling microbes. Taken together, these findings contribute to a richer understanding of how biochemical NO emissions in estuarine wetland sediments respond to salinity gradients.

Synergistic effects of phytohormones and membrane transporters in plant salt stress mitigation

Plants are frequently exposed to high salinity, negatively affecting their development and productivity. This review examined the complex roles of membrane transporters (MTs) and phytohormones in mediating salt stress. MTs are crucial in capturing sodium ions (Na+) and maintaining a delicate balance between sodium (Na+) and potassium (K+), essential for supporting cellular homeostasis and enhancing overall plant health. These MTs were instrumental in regulating ion balance and promoting the absorption and segregation of vital nutrients, thereby enhancing salt stress tolerance. Various plant hormones, including abscisic acid, auxin, ethylene, cytokinin, and gibberellins, along with gaseous growth regulators such as nitric oxide and hydrogen sulfide, collaborate to regulate and synchronize numerous aspects of plant growth, development, and stress responses to environmental factors. These transporters and other phytohormones, including brassinosteroids, melatonin, and salicylic acid, also collaborated to initiate adaptation processes, such as controlling osmotic pressure, removing ions, and initiating stress signaling pathways. This study consolidated the advancements in understanding the molecular and physiological processes contributing to plant salt tolerance, emphasizing the intricate relationships between MTs and phytohormones. The aim was to elucidate these interactions to promote further research and develop strategies for enhancing plant salt tolerance.

AcMYB176-Regulated AcCHS5 Enhances Salt Tolerance in Areca catechu by Modulating Flavonoid Biosynthesis and Reactive Oxygen Species Scavenging

High-salinity stress induces severe oxidative damage in plants, leading to growth inhibition through cellular redox imbalance. Chalcone synthase (CHS), a pivotal enzyme in the flavonoid biosynthesis pathway, plays critical roles in plant stress adaptation. However, the molecular mechanisms underlying CHS-mediated salt tolerance remain uncharacterized in Areca catechu L., a tropical crop of high economic and ecological significance. Here, we systematically identified the CHS gene family in A. catechu and revealed tissue-specific and salt-stress-responsive expression patterns, with AcCHS5 exhibiting the most pronounced induction under salinity. Transgenic Arabidopsis overexpressing AcCHS5 displayed enhanced salt tolerance compared to wild-type plants, characterized by elevated activities of antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), increased flavonoid accumulation, and reduced reactive oxygen species (ROS) accumulation. Furthermore, we identified the transcription factor AcMYB176 as a direct activator of AcCHS5 through binding to its promoter. Our findings demonstrate that the AcMYB176-AcCHS5 regulatory module enhances salt tolerance by orchestrating flavonoid biosynthesis and ROS scavenging. This study provides functional evidence of CHS-mediated salt adaptation in A. catechu and highlights its potential for improving stress resilience in tropical crops.

Integrative analysis of transcriptome and metabolism reveals functional roles of redox homeostasis in low light and salt combined stress in Leymus chinensis

Salt stress is one of the major limiting factors of Leymus chinensis (named sheepgrass) growth, which accelerates inhibitive effects that are particularly concomitant with low light regimes (LL-Salt). However, little is known about physiological and molecular mechanisms under such LL-Salt in sheepgrass. This study aims to uncover the key reprogrammed metabolic pathways induced by LL-Salt through an integrated analysis of transcriptome and metabolism. Results suggested that the growth of sheepgrass seedlings was dramatically inhibited with a ranging of 8 to 20% reduction in Fv/Fm in LL-Salt combined treatments. Catalase activities were increased by 40% in LL but significantly decreased in salt stress, ranging from 15 to 46%. Both transcriptome and metabolism analysis reveal that carbon metabolism pathways were significantly enriched in the differentially expressed genes with downregulation by both LL and salt stress treatment. Metabolites involved in the photorespiration pathway, including serine and glycolate, were downregulated in LL while upregulated in salt stress treatment, with the same pattern of expression levels of a photorespiration regulatory gene, glycolate oxidase. Collectively, we found that serval antioxidant redox pathways, including photorespiration, GSG/GSSH redox, and ABA signaling, participated in response to LL and salt combined events and highlighted the roles of cellular redox homeostasis in LL-Salt response in sheepgrass.

Natural variation in salt-induced changes in root:shoot ratio reveals SR3G as a negative regulator of root suberization and salt resilience in Arabidopsis

Soil salinity is one of the major threats to agricultural productivity worldwide. Salt stress exposure alters root and shoots growth rates, thereby affecting overall plant performance. While past studies have extensively documented the effect of salt stress on root elongation and shoot development separately, here we take an innovative approach by examining the coordination of root and shoot growth under salt stress conditions. Utilizing a newly developed tool for quantifying the root:shoot ratio in agar-grown Arabidopsis seedlings, we found that salt stress results in a loss of coordination between root and shoot growth rates. We identify a specific gene cluster encoding domain-of-unknown-function 247 (DUF247), and characterize one of these genes as Salt Root:shoot Ratio Regulator Gene (SR3G). Further analysis elucidates the role of SR3G as a negative regulator of salt stress tolerance, revealing its function in regulating shoot growth, root suberization, and sodium accumulation. We further characterize that SR3G expression is modulated by WRKY75 transcription factor, known as a positive regulator of salt stress tolerance. Finally, we show that the salt stress sensitivity of wrky75 mutant is completely diminished when it is combined with sr3g mutation. Together, our results demonstrate that utilizing root:shoot ratio as an architectural feature leads to the discovery of a new stress resilience gene. The study's innovative approach and findings not only contribute to our understanding of plant stress tolerance mechanisms but also open new avenues for genetic and agronomic strategies to enhance crop environmental resilience.

Genome-Wide Identification of the Cation/Proton Antiporter (CPA) Gene Family and Expression Pattern Analysis Under Salt Stress in Winter Rapeseed (Brassica rapa L.)

The CPA gene family regulates ionic balance and pH homeostasis in cells, significantly contributing to plant stress tolerance. In this study, a total of 63 BrCPA gene family members were identified in the whole genome of Brassica rapa L. (B. rapa), and the three subfamily members were BrNHX (9), BrKEA (15), and BrCHX (39), respectively. The members of the BrCPA gene family encoded 303-1259 amino acids, with molecular weights in the range of 32,860.39~139,884.73 kDa, distributed on 10 chromosomes, and contained 17 conserved motifs, BrNHX and BraKEA, and the BrCPA gene family members had the same molecular weights on 10 chromosomes and contain 17 conserved motifs. The BrNHX and BraKEA subfamilies have more exons than the BrCHX subfamily. An analysis of promoter cis-acting elements in the BrCPA gene showed that members of this gene family contain TC-rich, LTR, MBS, and ARE stress response elements. In addition, transcriptome analysis revealed the expression of CPA genes in B. rapa under salt stress. The selected genes were verified by RT-qPCR. By detecting the Na+ and K+ flow rates in the root and chloroplast cells of salt-tolerant and salt-sensitive varieties after salt treatment, it was found that the rate of Na+ and K+ efflux from the root and chloroplast cells of salt-sensitive varieties was significantly higher than that of salt-tolerant varieties. This investigation marks the first systematic identification of the CPA gene family in B. rapa. This study further explores its expression patterns and the efflux rates of Na+ and K+ across salt-tolerant varieties, providing a theoretical basis for understanding the role of the CPA gene family in the salt stress response of B. rapa.

Trichoderma asperellum 22043: Inoculation Promotes Salt Tolerance of Tomato Seedlings Through Activating the Antioxidant System and Regulating Stress-Resistant Genes

Salt stress poses a major threat to plant growth, and breeding for salt-tolerant varieties is not always successful to ameliorate this threat. In the present experiment, the effect of T. asperellum 22043 inoculation on the growth of salt-stressed tomatoes and the mechanisms by which it improves salt tolerance were investigated. It was observed that tomato plants treated with T. asperellum 22043 spore suspension under salt tress (50 and 100 mM NaCl) consistently exhibited higher seeds germination, seedling survival rate, plant height, and chlorophyll content, but lower malondialdehyde and proline contents than the plants treated without the Trichoderma. T. asperellum 22043 effectively improved the stress resistance of tomato through regulating the transcriptional levels of reactive oxygen species (ROS) scavenging enzyme gene expression to modulate the activity of ROS scavenging enzymes and the expression of the genes related to transporter and aquaporin to maintain the balance of cell Na+. In conclusion, T. asperellum 22043 can enhance tomato seedlings' salt tolerance by activating the antioxidant system and regulating the expression of stress-resistant genes.

Physiol-biochemical, transcriptome, and root microstructure analyses reveal the mechanism of salt shock recovery in sugar beet

Soil salinity substantially limits agricultural productivity, necessitating a sound understanding of salt-tolerance mechanisms in key crops for their improved breeding. Despite being a staple sugar crop with strong salt tolerance, sugar beet (Beta vulgaris L.), remains underexplored for its transcriptional responses to salt shock. This study compared the physiological traits, root structure, and full-length transcriptomes of salt-tolerant (T510) and salt-sensitive (S210) sugar beet varieties during stages of osmotic stress (0-24 h) and ionic stress (1-7 d) after incurring salt shock. The results show that T510 recovered faster, maintaining a higher water potential (WP), better osmotic regulation, lower reactive oxygen species (ROS) levels, and a balanced Na+/K+ ratio. Furthermore, while under osmotic stress, T510 exhibited extensive transcriptional reprogramming to enhance its photosynthetic efficiency and carbon assimilation via the C4-dicarboxylic acid (C4) cycle, which compensated for salt shock-induced disruptions to the Calvin-Benson (C3) cycle. Notably, elevated activity of ascorbate peroxidase (APX) and glutathione S-transferase (GST), driven by greater gene expression, enhanced the scavenging of ROS. In tandem, T510 synthesized more lignin than S210, and adapted its root microstructure to maintain water and nutrient transport functioning in the face of high salinity. Overall, these findings provide insights into the physiological, transcriptomic, and structural adaptations enabling salt tolerance in sugar beet plants, thus offering valuable strategies for strengthening crop resilience through molecular breeding.

An Integrated Method for Evaluation of Salt Tolerance in a Tall Wheatgrass Breeding Program

Tall wheatgrass, a perennial forage grass renowned for its salt-alkali tolerance, has recently been proposed as a key species for planting in coastal saline-alkaline lands to establish a "Coastal Grass Belt". Highly salt-tolerant and high-yielding varieties are essential to achieve this objective. To enhance breeding efficiency, a method integrating seed germination, seedling emergence, and seedling growth was established to evaluate salt tolerance in tall wheatgrass. Germination tests revealed that under 250 mM NaCl, 150 mM Na2SO4, 150 mM NaHCO3, or 100 mM Na2CO3, the relative seed germination rates were 31.5%, 65.4%, 68.2%, and 32.6%, respectively, compared to the non-stress condition. Germination tests can use 250 mM NaCl and 100 mM Na2CO3 to assess tall wheatgrass tolerance to neutral and sodic salt stress, respectively. In addition, 250 mM NaCl or saline water with ECw = 6.6 dS m-1 resulted in relative seedling emergence rates of 52% and 59.8%, respectively, compared to the non-stress condition. Seedling hydroponic culture demonstrated that exposure to 300 mM NaCl resulted in relative total dry weight, shoot dry weight, and root dry weight of 38.2%, 35.7% and 50%, respectively, compared to the non-stress condition. Salt-response genes exhibited differential expression in tall wheatgrass under long-term and short-term salt stress. Interestingly, the expression levels of NHX7.1 and NCL1 were significantly higher in salt-tolerant lines compared to salt-sensitive lines. Based on an integrated evaluation of seed germination, seedling emergence, and seedling growth, five out of the 28 tall wheatgrass lines were identified as salt-tolerant. Additionally, two Tritipyrum lines, derived from the cross of Triticum aestivum cv. Xinong 6028 and Thinopyrum ponticum line Zhongyan 1, were found to inherit salt tolerance from tall wheatgrass. Collectively, this work provided an integrated method for salt tolerance testing in a tall wheatgrass breeding program.

Ameliorative effects of SL on tolerance to salt stress on pepper (Capsicum annuum L.) plants

Salinity is one of the most important problems that threaten agricultural production, especially in arid and semiarid areas. Strigolactones (SLs) are important in providing tolerance to various abiotic stresses in plants. The study was carried out in a hydroponic system to determine the effects of external GR24 (were applied as a foliar spray; 0, 10, and 20 μM) applications at different doses on plant growth and some physiological, biochemical, and gene expression in two pepper genotype (Yalova and Maraş) grown under salt stress (0 and 100 mM NaCl). Plants were harvested and measured 10 days after the NaCl treatments. At the end of the research, it was determined that salt stress negatively affected plant growth in both genotype. Still, SL applications positively affected plant development both under normal and salt stress. While salt stress increased the amount of hydrogen peroxide (H2O2) and malondialdehyde (MDA), SL application caused a decrease in these parameters. Salt stress negatively affected the amount of chlorophyll and photosynthetic properties in both genotype, whereas SL applications mitigated this negative effect. SL applications caused a significant increase in antioxidant enzyme activities under both normal and salt stress conditions. SL content, which decreased with salt stress, increased with exogenous SL application. The content of other plant nutrients except sodium (Na) and chloride (Cl) decreased significantly in pepper seedlings grown under salt stress. External SL applications increased the uptake of these nutrients, especially under salt stress. In addition, the expression levels of CIPK3, CBL2, CCD7, DMAX2, PsbA, PsbB, PsbP1, TIP1;2, TIP5;1, SOS1, SOS2 and HKT2;2 genes were investigated in this study. It was observed that the expression levels of CCD7, DMAX2, SOS1, SOS2, and HKT2;2 genes increased with salinity stress, especially in the Maraş genotype, while SL applications decreased these expression levels. In the study, it was determined that especially exogenous 20 μM SL application could significantly reduce the negative effects of salt stress in pepper.

Combined transcriptomic and metabolomic analysis revealed the salt tolerance mechanism of Populus talassica × Populus euphratica

BACKGROUND

To investigate the salt tolerance of Populus talassica × Populus euphratica, morphological and physiological parameters were measured on the second day after the 15th, 30th and 45th days of NaCl treatment, revealing significant effects of NaCl on growth. To further elucidate the mechanisms underlying salt tolerance, transcriptomic and metabolomic analysis were conducted under different NaCl treatments.

RESULTS

The results of morphological and physiological indexes showed that under low salt treatment, P. talassica × P. euphratica was able to coordinate the growth of aboveground and belowground parts. Under high salt concentration, the growth and water balance of P. talassica × P. euphratica were markedly inhibited. The most significant differences between treatments were observed on the second day after the 45th day of NaCl treatment. Transcriptomic analysis showed that the pathways of gene enrichment in the roots and stems of P. talassica × P. euphratica were different in the salt resistance response. And it involves several core pathways such as plant hormone signal transduction, phenylpropanoid biosynthesis, MAPK signaling pathway-plant, plant- pathogen interaction, carbon metabolism, biosynthesis of amino acids, and several key Transcription factors (TFs) such as AP2/ERF, NAC, WRKY and bZIP. Metabolomic analysis revealed that KEGG pathway enrichment analysis showed unique metabolic pathways were enriched in P. talassica × P. euphratica under both 200 mM and 400 mM NaCl treatments. Additionally, while there were some differences in the metabolic pathways enriched in the roots and stems, both tissues commonly enriched pathways related to the biosynthesis of secondary metabolites, biosynthesis of cofactors, biosynthesis of amino acids, flavonoid biosynthesis, and ABC transporters. Association analysis further indicated that biosynthesis of amino acids and plant hormone signal transduction pathway play key roles in the response of P. talassica × P. euphratica to salt stress. The interactions between the differentially expressed genes (DEGs) and several differentially accumulated metabolites (DAMs), especially the strong association between LOC105124002 and Jasmonoyl-L-Isoleucine (pme2074), were again revealed by the interactions analysis.

CONCLUSIONS

In this study, we resolved the changes of metabolic pathways in roots and stems of P. talassica × P. euphratica under different NaCl treatments and explored the associations between characteristic DEGs and DAMs, which provided insights into the mechanisms of P. talassica × P. euphratica in response to salt stress.

Proteomic analysis of the regulatory network of salt stress in Chrysanthemum

BACKGROUND

Saline-alkali stress is one of the main abiotic stresses that constrains plant growth. Understanding the response mechanism of ornamental plants to saline-alkali stress is of great significance for improving saline-alkali landscape greening. Chrysanthemum is a good ornamental plant with strong resistance to stress, rich colors and easy management.

RESULTS

Using TMT quantitative proteomics technology, leave and root of Chrysanthemum that were either untreated or treated with 200 mM NaCl for 12 h, screened the differentially expressed proteins. The results showed that 66 and 452 differential proteins were present in leaves and roots after salt treatment, respectively. GO function is mainly related to carbohydrate and energy metabolism, hormone response, antioxidant response and membrane protein activity. The KEGG metabolic pathway is mainly concentrated in glycine metabolism, glutathione metabolic pathway, carbon fixation in prokaryotes, 2-oxy-carboxylic acid metabolism. Combining transcripto-proteomics, GO and KEGG analyses revealed significant enrichment in starch anabolic catabolism, redox processes, ion homeostatic transport, phenylpropane biosynthesis.

CONCLUSIONS

Under salt stress, the active pathways of carbohydrate and energy metabolism and glutathione metabolism enable plants to accumulate more energy substances and improve antioxidant capacity, which may play a safeguarding role in maintaining growth and development and mitigating reactive oxygen species damage in Chrysanthemum under stress. The purpose of this study was to screen key proteins and regulatory networks through proteomic assay, and reveal the molecular mechanism of response to salt stress. The research not only provides resources for salt-tolerant breeding of Chrysanthemum but also offers theoretical support for agricultural production and ecological environmental protection.

DRB1 and DRB2 Are Required for an Appropriate miRNA-Mediated Molecular Response to Salt Stress in Arabidopsis thaliana

In plants, microRNAs (miRNAs) and their target genes have been demonstrated to form an essential component of the molecular response to salt stress. In Arabidopsis thaliana (Arabidopsis), DOUBLE-STRANDED RNA BINDING1 (DRB1) and DRB2 are required to produce specific miRNA populations throughout normal development and in response to abiotic stress. The phenotypic and physiological assessment of 15-day-old wild-type Arabidopsis seedlings, and of the drb1 and drb2 mutants following a 7-day period of salt stress, revealed the drb2 mutant to be more sensitive to salt stress than the drb1 mutant. However, the assessment of miRNA abundance and miRNA target gene expression showed that the ability of both drb mutants to mount an appropriate miRNA-mediated molecular response to salt stress is defective. Furthermore, molecular profiling also showed that DRB1 and DRB2 are both required for miRNA production during salt stress, and that both a target transcript cleavage mode and a translational repression mode of RNA silencing are required to appropriately regulate miRNA target gene expression as part of the molecular response of Arabidopsis to salt stress. Taken together, the phenotypic, physiological, and molecular analyses performed here clearly show that all components of the miRNA pathway must be fully functional for Arabidopsis to mount an appropriate miRNA-mediated molecular response to salt stress.

Label-Free Proteomics Reveals the Response of Oat (Avena sativa L.) Seedling Root Respiratory Metabolism to Salt Stress

Soil salinity is among the crucial factors influencing agricultural productivity of crops, including oat. The respiratory metabolic pathways are of great significance for plants to adapt to salt stress, but current research is limited and there are few reports on salt-tolerant crops such as oat, which is necessary to conduct in-depth research. In this study, we conducted a pot experiment to determine the effects of salt stress on oat root growth and respiratory metabolism. Three salt stress levels-control (CK), moderate, and severe-were applied to compare the salt tolerance of the salt-tolerant cultivar Bai2 and the salt-sensitive cultivar Bai5. We selected oat roots at the seedling stage as the research focus and analyzed fresh root samples using an Oxytherm liquid-phase oxygen electrode, a digital scanner, and proteomics. The results showed that with an increased concentration of salt stress, the dry and fresh weight, root-shoot ratio, total root length, root surface area, root volume, and average diameter of the two oat cultivars showed a decreasing trend. Compared with CK, the total root respiration rate of Bai2 under moderate and severe stress decreased by 15.6% and 28%, respectively, and that of Bai5 decreased by 70.4% and 79.0%, respectively. After quantitative analysis of 18 oat root samples from the 2 cultivars using the label-free method, 7174 differential proteins were identified and 63 differential proteins were obtained, which involved 7 functional categories. In total, 111 differential proteins were specifically expressed in the root of the salt-tolerant cultivar Bai2, involving 12 functional categories. Through interaction network analysis, the proteins differentially expressed between the salt treatment and CK groups of the salt-tolerant cultivar Bai2 were analyzed. In total, five types of differentially expressed proteins interacting with each other were detected; these mainly involved antioxidant enzymes, pyruvate metabolism, glycolysis, tricarboxylic acid cycle, and energy metabolism pathways. Salt stress promoted the respiration rate of oat root glycolysis. The respiration rate of the tricarboxylic acid pathway decreased with increased salt stress concentration, while the respiration rate of the pentose phosphate pathway increased. Compared with CK, following moderate and severe salt stress treatment, alcohol dehydrogenase activity in Bai2 increased by 384% and 145%, respectively, while that of Bai5 increased by 434% and 157%, respectively. At increased salt stress concentrations, Bai2 mainly used pyruvate-ethanol fermentation for anaerobic respiration, while Bai5 mainly used pyruvate-lactic acid fermentation for anaerobic respiration. This significant discovery revealed for the first time from the perspective of respiratory metabolism that different salt-tolerant oat cultivars adapt to salt stress in different ways to maintain normal growth and development. The experimental results provide new insights into plant adaptation to salt stress from the perspective of respiratory metabolism.

Unveiling the Impact of Organic Fertilizer on Rice (Oryza sativa L.) Salinity Tolerance: Insights from the Integration of NDVI and Metabolomics

Soil salinization threatens global agriculture, reducing crop productivity and food security. Developing strategies to improve salt tolerance is crucial for sustainable agriculture. This study examines the role of organic fertilizer in mitigating salt stress in rice (Oryza sativa L.) by integrating NDVI and metabolomics. Using salt-sensitive (19X) and salt-tolerant (HHZ) cultivars, we aimed to (1) evaluate changes in NDVI and metabolite content under salt stress, (2) assess the regulatory effects of organic fertilizer, and (3) identify key metabolites involved in stress response and fertilizer-induced regulation. Under salt stress, survival rate of the 19X plants dropped to 6%, while HHZ maintained 38%, with organic fertilizer increasing survival rate to 25% in 19X and 66% in HHZ. NDVI values declined sharply in 19X (from 0.56 to <0.25) but remained stable in HHZ (~0.56), showing a strong correlation with survival rate (R2 = 0.87, p < 0.01). NDVI provided a dynamic, non-destructive assessment of rice health, offering a faster and more precise evaluation of salt tolerance than survival rate analysis. Metabolomic analysis identified 12 key salt-tolerant metabolites, including citric acid, which is well recognized for regulating salt tolerance. HTPA, pipecolic acid, maleamic acid, and myristoleic acid have previously been reported but require further study. Additionally, seven novel salt-tolerant metabolites-tridecylic acid, propentofylline, octadeca penten-3-one, 14,16-dihydroxy-benzoxacyclotetradecine-dione, cyclopentadecanolide, HpODE, and (±)8,9-DiHETE-were discovered, warranting further investigation. Organic fertilizer alleviated salt stress through distinct metabolic mechanisms in each cultivar. In 19X, it enhanced antioxidant defenses and energy metabolism, mitigating oxidative damage and improving fatty acid metabolism. In contrast, HHZ primarily benefitted from improved membrane stability and ion homeostasis, reducing lipid peroxidation and oxidative stress. These findings primarily support the identification and screening of salt-tolerant rice cultivars while also highlighting the need for cultivar-specific fertilization strategies to optimize stress resilience and crop performance. Based on the correlation analysis, 26 out of 53 differential metabolites were significantly correlated with NDVI, confirming a strong association between NDVI shifts and key metabolic changes in response to salt stress and organic fertilizer application. By integrating NDVI and metabolomics, this study provides a refined method for evaluating salt stress responses, capturing early NDVI changes and key salinity stress biomarkers. This approach may prove valuable for application in salt-tolerant variety screening, precision agriculture, and sustainable farming, contributing to scientific strategies for future crop improvement and agricultural resilience.

Physiological, ionomic, transcriptomic and metabolomic analyses reveal molecular mechanisms of root adaption to salt stress in water spinach

Water spinach (Ipomoea aquatica Forsk.) is an important leaf vegetable affected by salt stress, however, little is known about its salt adaption mechanism. Here, we integrated physiomics, ionomics, transcriptomics, and metabolomics to analyze the root adaptation response of two water spinach varieties, BG (salt-tolerant) and MF (salt-sensitive), at 150 mM NaCl. The results showed that compared with MF, BG significantly reduced the content of malondialdehyde (MDA) and H2O2, and increased catalase (CAT) activity and proline content. Ionome analysis demonstrated that BG significantly reduced Na+ accumulation and increased K+ level to reduce the toxicity of Na+, compared to MF. Weighted gene co-expression network analysis (WGCNA) revealed that key transcription factors such as HSFA4A, bHLH093, and IDD7, which were only up-regulated in BG. Multi-omics revealed that BG reprogrammed key pathways: starch and sucrose metabolism, as well as galactose metabolism, leading to decreased amylose production and increased sucrose and galactose levels, helping to maintain cellular osmotic balance in response to salt stress. These findings provide insight into transcriptional regulation in response to salt stress, which could advance the genetic enhancement of water spinach.

Stimulatory Effect of Delonix regia Flower Extract in Protecting Syzygium cumini Seedlings from Salinity

Syzygium cumini (L.) Skeels (jamun) is an ornamental tree species that is sensitive to salinity. Salinity stress is a major challenge, particularly in regions with saline irrigation water. In the present study, the ameliorative potential of foliar application of an aqueous extract of Delonix regia (Poinciana) flowers (PFE) to saline water-irrigated jamun seedlings was investigated over a period of two years. PFE was effective in mitigating the harmful effects of salinity on plant growth, physiology, and biochemistry. Salinity-induced reductions in plant height, leaf area, and biomass which were significantly alleviated by PFE foliar application. The extract also enhanced antioxidant activity, as indicated by increased ferric reducing antioxidant potential (FRAP) and phenolic content, while also reducing hydrogen peroxide (H2O2) levels and membrane damage as indicated by the accumulation of malondialdehyde (MDA). Additionally, the foliar application of PFE promoted the accumulation of free proline, an essential osmo-protectant, further enhancing the plant's resilience to salinity stress. These findings highlight the potential of PFE as an eco-friendly bio-stimulant to improve salinity tolerance in jamun and pave the way for sustainable salinity management strategies in other crops as well.

Multi-Omic Advances in Olive Tree (Olea europaea subsp. europaea L.) Under Salinity: Stepping Towards 'Smart Oliviculture'

Soil salinisation is threatening crop sustainability worldwide, mainly due to anthropogenic climate change. Molecular mechanisms developed to counteract salinity have been intensely studied in model plants. Nevertheless, the economically relevant olive tree (Olea europaea subsp. europaea L.), being highly exposed to soil salinisation, deserves a specific review to extract the recent genomic advances that support the known morphological and biochemical mechanisms that make it a relative salt-tolerant crop. A comprehensive list of 98 olive cultivars classified by salt tolerance is provided, together with the list of available olive tree genomes and genes known to be involved in salt response. Na+ and Cl- exclusion in leaves and retention in roots seem to be the most prominent adaptations, but cell wall thickening and antioxidant changes are also required for a tolerant response. Several post-translational modifications of proteins are emerging as key factors, together with microbiota amendments, making treatments with biostimulants and chemical compounds a promising approach to enable cultivation in already salinised soils. Low and high-throughput transcriptomics and metagenomics results obtained from salt-sensitive and -tolerant cultivars, and the future advantages of engineering specific metacaspases involved in programmed cell death and autophagy pathways to rapidly raise salt-tolerant cultivars or rootstocks are also discussed. The overview of bioinformatic tools focused on olive tree, combined with machine learning approaches for studying plant stress from a multi-omics perspective, indicates that the development of salt-tolerant cultivars or rootstocks adapted to soil salinisation is progressing. This could pave the way for 'smart oliviculture', promoting more productive and sustainable practices under salt stress.

Implication of ribosomal protein in abiotic and biotic stress

MAIN CONCLUSION

This review article explores the intricate role, and regulation of ribosomal protein in response to stress, particularly emphasizing their pivotal role to ameliorate abiotic and biotic stress conditions in crop plants. Plants must coordinate ribosomes production to balance cellular protein synthesis in response to environmental variations and pathogens invasion. Over the past decade, research has revealed ribosome subgroups respond to adverse conditions, suggesting that this tight coordination may be grounded in the induction of ribosome variants resulting in differential translation outcomes. Furthermore, an increasing snumber of studies on plant ribosomes have made it possible to explore the stress-regulated expression pattern of ribosomal protein large subunit (RPL) and ribosomal protein small subunit (RPS) genes. In this perspective, we reviewed the literature linking ribosome heterogeneity to plants' abiotic and biotic stress responses to offer an overview on the expression and biological function of ribosomal components including specialized translation of individual transcripts and its implications for the regulation and expression of important gene regulatory networks, along with phenotypic analysis in ribosomal gene mutations in physiologic and pathologic processes. We also highlight recent advances in understanding the molecular mechanisms behind the transcriptional regulation of ribosomal genes linked to stress events. This review may serve as the foundation of novel strategies to customize cultivars tolerant to challenging environments without the yield penalty.